AS1170

Detailed description

Datasheet

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7.5.6

Operating mode and currents

The output currents and operating mode are selected according to the following table:

Table 6: Operating mode and current settings

Operating mode and currents

SCL and

SDA

STROBE

mode_setting

out_on

Condition

Mode

LED_OUT1/2 output

current

SCL low for

tTIMEOUT

(1)

X

X

X

If previous

operating mode was

indicator, assist light

or flash mode

Shutdown

all registers are

reset to their

default values

0

I²C

commands

are

accepted

X

10, 01 or 11

0

Standby

0

X

01

1

Indicator mode

or low current

pwm mode(3)

LED current is defined by

the 6LSB bits (bits 5...0) of

led_current1 and

led_current2 pwm

modulated with 31.25 kHz

defined by register

inct_pwm (1/ 16...4/16)

X

10

1

Assist light

mode

LED current is defined

by the 7LSB(2) bits (6...0) of

led_current1 and

led_current2

X

11

1

strobe_on

= 0

Flash mode;

Flash duration

defined by

flash_timeout

LED current is defined by

led_current1 and

led_current2 - the current

can be reduced during

flash, see Flash current

reductions below

0->1

strobe_on = 1 and

strobe_type = 0

1

strobe_on = 1 and

strobe_type = 1

Flash mode;

Flash duration

defined by

strobe input;

timeout defined

by flash_timeout

(1) SCL low for tTIMEOUT and operating mode is indicator, assist or flash mode then shutdown mode is entered.

(2) The MSB bit of this register not used to protect the LED; therefore the maximum assist light current = half the maximum flash

current.

(3) The low current mode is a general purpose PWM mode to drive less current through the LED in average, but keep the actual

pulsed current in a range where the light output from the LED is still specified. As only the 6 LSBs of led_current1 and

led_current2 are used the maximum current is limited to 1/4 of the maximum flash current.